`IllegalArgumentException` when attempting to decode invalid UTF-8 surrogate by SnakeYAML (oss-fuzz 50431)

[cowtowncoder]

(note: issue found by OSS-Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=50431)

Looks like there is an uncaught IllegalArgumentException for certain input; problem caught by Fuzzing.
Stack trace looks like

== Java Exception: java.lang.IllegalArgumentException: Not a valid Unicode code point: 0xE30EEE
	 at java.base/java.lang.Character.toChars(Character.java:9175)
	 at org.yaml.snakeyaml.scanner.ScannerImpl.scanFlowScalarNonSpaces(ScannerImpl.java:1973)
	 at org.yaml.snakeyaml.scanner.ScannerImpl.scanFlowScalar(ScannerImpl.java:1919)
	 at org.yaml.snakeyaml.scanner.ScannerImpl.fetchFlowScalar(ScannerImpl.java:1068)
	 at org.yaml.snakeyaml.scanner.ScannerImpl.fetchDouble(ScannerImpl.java:1050)
	 at org.yaml.snakeyaml.scanner.ScannerImpl.fetchMoreTokens(ScannerImpl.java:436)
	 at org.yaml.snakeyaml.scanner.ScannerImpl.checkToken(ScannerImpl.java:251)
	 at org.yaml.snakeyaml.parser.ParserImpl$ParseImplicitDocumentStart.produce(ParserImpl.java:214)
	 at org.yaml.snakeyaml.parser.ParserImpl.peekEvent(ParserImpl.java:166)
	 at org.yaml.snakeyaml.parser.ParserImpl.getEvent(ParserImpl.java:176)
	 at com.fasterxml.jackson.dataformat.yaml.YAMLParser.nextToken(YAMLParser.java:403)

I think SnakeYAML should catch the problem, re-throw -- content is invalid, but should not get through as IAE.

I created #401 for the test.

[asomov]

@cowtowncoder thank you for the info:
https://bitbucket.org/snakeyaml/snakeyaml/issues/576

[cowtowncoder]

@asomov Thanks! For some reason I seem to lack access to see it tho...

[asomov]

@cowtowncoder because of the spam attack I had to close the issue tracker. I hope I will open it soon

[cowtowncoder]

Still open but will be resolved by SnakeYAML release after 2.0 (likely 2.1)

[asomov]

Hopefully 2.1 will be released in August 2023

[cowtowncoder]

Fixed via #426