Valid style JSON causes infinite loading

Maputnik version: > 1.6.1
Browser: > Chrome
OS: macOS

Description of the bug:

Steps to reproduce the behavior:

1. Have a style with a layer definition like this:

{
  "id": "water_lines_labels",
  "type": "symbol",
  "source": "osm",
  "source-layer": "water_lines",
  "minzoom": 14,
  "maxzoom": 24,
  "layout": {
    "visibility": "visible",
    "text-field": "{name}",
    "symbol-placement": "line",
    "text-pitch-alignment": "auto",
    "text-rotation-alignment": "auto",
    "text-size": 11,
    "text-anchor": "bottom",
    "text-letter-spacing": 0,
    "text-font": [
      "Backpack Regular",
      "Arial Unicode"
    ]
  },
  "paint": {
    "text-color": "rgba(255, 255, 255, 1)",
    "text-halo-color": "rgba(116, 207, 240, 1)",
    "text-halo-width": 1
  },
  "symbol-spacing": 500, 
  "text-anchor": "bottom"
}

2. Upon trying to load this style, the editor enters an infinite loop of HTTP requests and never stops. No error message or console output is displayed.
3. The error seems to be caused by symbol-spacing and text-anchor properties being in the root of the layer (which is malformed)

I had to binary-search by hand my style file to find it, so I hope this helps someone.

No source file or test is named. Reproduce the issue with the supplied style, then trace the style-loading and validation entry points while watching the repeated HTTP requests. Done means malformed root-level properties produce a clear error or terminate loading instead of causing an infinite request loop, with a regression test if the project’s existing test structure supports it.