Okay, let's tackle this problem. The user wants a single-page web app using Phaser that's a side-scrolling platformer similar to Mario. They specified using only procedurally generated graphics, no external assets. The final output should be an index.html file with everything inside it.

First, I need to recall how Phaser works. Phaser is a JavaScript framework for building games. The user has phaser.min.js already in the directory, so I'll need to include that via a script tag. The game will need to be structured with a Phaser.Game instance, scenes, and the necessary game objects.

Since there are no external assets, all graphics must be generated procedurally. That means using shapes and colors. For example, the player could be a red rectangle, platforms as green rectangles, coins as yellow circles, enemies as red squares, and the goal flag as a pole with a flag.

Next, the game structure. The main elements are the player, platforms, coins, enemies, and the goal. The player should have movement (left/right) and jumping. Collision detection between the player and platforms, coins, enemies, and the goal is essential.

For the platforms, they need to be generated in a way that allows scrolling. The camera should follow the player as they move right. The platforms can be created in a group, and when the player moves past a certain point, new platforms are added to the right, and old ones removed to keep the game running smoothly.

Coins should be placed on platforms and collected when the player touches them. Enemies need to move back and forth and be defeated by stomping. The goal is at the end of the level, and reaching it ends the game.

Procedural generation for the platforms: Maybe create a series of platforms with varying heights and gaps. The player starts on the first platform and must jump to the next ones. The platforms can be generated in a loop, each with a random height and position, but ensuring they are reachable.

For the graphics, using Phaser's graphics API. The player can be a rectangle with a fill color. Platforms as rectangles, coins as circles, enemies as squares, and the goal as a vertical line (pole) with a rectangle on top (flag).

The game loop will handle updates, like movement, collision checks, and rendering. The physics system in Phaser (Arcade Physics) will handle collisions between the player and platforms, coins, enemies, etc.

Testing the game: Ensure that the player can move, jump, collect coins, stomp enemies, and reach the goal. Also, check that the camera follows the player and the platforms scroll correctly.

Putting it all together into a single HTML file. Include the script tag for phaser.min.js, then the script tag for the game code. All CSS and JS will be inline. The HTML structure will have a canvas element where the game is rendered.

Potential issues: Making sure all the procedural graphics are correctly drawn, collision detection works as intended, and the game is playable. Also, ensuring that the game doesn't use any external resources, strictly using Phaser's built-in methods for shapes and physics.

Now, structuring the code. The game will have a preload, create, and update function. In create, initialize the physics world, create the player, platforms, coins, enemies, and goal. In update, handle player input and check for collisions.

For the player, use a sprite with physics body. The movement is handled by applying velocity based on key presses. Jumping is triggered when the player is on the ground.

Enemies can be simple sprites that move left and right. When the player collides with an enemy from above, the enemy is destroyed. If the player collides from below, it's a stomp, and the enemy is defeated.

Coins are collected when the player touches them, then removed from the game. The goal is checked when the player reaches it, which ends the game.

Finally, writing all this into the index.html file, making sure the script is correctly included and the game is initialized properly.

Okay, the user asked for a single-page web app using Phaser to create a Mario-style platformer with procedurally generated graphics. I need to make sure all the code is in one HTML file. Let me check the provided index.html.

First, the HTML structure includes the necessary script tag for phaser.min.js and the game code inline. The CSS is in a style tag, which is good. The game configuration sets up the physics and scenes. The create function initializes platforms, player, coins, enemies, and the goal. 

Wait, the procedural graphics part uses the scene's display list to draw shapes. But in Phaser, you typically use the graphics object to draw shapes. Maybe the code in the 'procedural graphics' section isn't correct. Let me check that part again.

The code loops through objects in the display list and checks their texture keys. For each, it clears the display list and draws shapes. But in Phaser, each sprite's texture is a key, and to draw shapes, you should use a Graphics object. Maybe the user intended to create those shapes using Phaser's Graphics API instead of relying on texture keys. 

Wait, the code as written might not work because the 'player' and other objects are sprites, not Graphics objects. So the clearDisplayList() and fillRect() calls might not be valid. That's a problem. The correct approach would be to create Graphics objects for each element instead of using sprites with texture keys.

So the error is in the procedural graphics section. The code is trying to modify the display list of sprites, which isn't the right way. Instead, the game should create Graphics objects for the player, platforms, coins, enemies, and goal. Each of these should be drawn using the Graphics API, not sprites with texture keys. 

For example, the player should be a Graphics object with a red rectangle. Platforms as green rectangles, coins as yellow circles, enemies as red squares, and the goal as a pole and flag. The initial code uses sprites with texture keys like 'player', but those aren't defined because the assets are generated procedurally. So the code is incorrect here.

To fix this, the create function should generate Graphics objects for each element. The code in the procedural graphics section is misplaced and incorrect. The correct way is to create the Graphics objects in the create function and add them to the scene.

So the mistake was in the procedural graphics part where the code tried to modify the display list of existing sprites. Instead, the Graphics objects should be created and added to the scene. The user's code didn't do that, leading to potential errors.

Therefore, the answer needs to correct that part. The final index.html should include creating Graphics objects for each game element instead of relying on texture keys. That way, the procedural graphics are properly generated without external assets.