Interface breaks on glyph in json

Describe the bug

Recaf GUI breaks when attempting to display a text file with glyph in json.

To Reproduce

Steps to reproduce the behavior:

1. Create jar file.
2. Add a text file with contents:

[
  {
    "": "🌉"
  }
]

1. Load in recaf and open text file.

Exception

If applicable, add the exception/stacktrace.

00:44:14.798 [ForkJoinPool-1-worker-5] DEBUG: Generated 0 phantom classes in 49 ms
java.lang.ArrayIndexOutOfBoundsException: Index -1 out of bounds for length 32
	at com.sun.prism.impl.GlyphCache.getCachedGlyph(GlyphCache.java:332)
	at com.sun.prism.impl.GlyphCache.render(GlyphCache.java:148)
	at com.sun.prism.impl.ps.BaseShaderGraphics.drawString(BaseShaderGraphics.java:2101)
	at com.sun.javafx.sg.prism.NGText.renderText(NGText.java:312)
...

https://pastebin.com/f7DKDMbF

Screenshots

Tested on OpenJDK Runtime Environment AdoptOpenJDK-11.0.11+9 (build 11.0.11+9) OpenJDK Runtime Environment AdoptOpenJDK-16.0.1+9 (build 16.0.1+9) Ubuntu 20.04

[nothub]

recaf updated javafx to 15.0.1 after deleting the old dependencies, everything works as expected now, thanks 👍

[Col-E]

I’ve removed the unnecessary version check, so in the next release it will pull only newer JFX versions. But existing cached jars will need to be manually cleared by the user.