StateMetadataUtils hides actual errors

[juhoautio]

Looks like not catching Throwable #13 wasn't enough yet.

I got this error:

java.lang.IllegalStateException: Cannot read state of a stateless operator.
	at com.king.bravo.reader.OperatorStateReader.lambda$readKeyedStates$6(OperatorStateReader.java:101)
	at java.util.Optional.orElseThrow(Optional.java:290)
	at com.king.bravo.reader.OperatorStateReader.readKeyedStates(OperatorStateReader.java:101)

The actual cause was another Exception, which got silently ignored here:

bravo/bravo/src/main/java/com/king/bravo/utils/StateMetadataUtils.java

Lines 137 to 139 in 6013d09

	} catch (Exception e) {
	return Optional.empty();
	}

Any reason to return Optional.empty() here instead of throwing a runtime exception (that wraps the original exception)?

I found the actual exception with debugger:

java.lang.RuntimeException: org.apache.flink.core.fs.UnsupportedFileSystemSchemeException: Could not find a file system implementation for scheme 's3'. The scheme is not directly supported by Flink and no Hadoop file system to support this scheme could be loaded.

Yeah, apparently that happens because I had copied the savepoint from its original s3 location to my local machine (is it really so that even savepoint folders can't be moved anywhere from their original location?)

[gyfora]

I think Flink savepoints have absolute path references inside their metadata so you cant really move them around. :/

But you are probably write we should just throw these exceptions