SoySyntaxException is an abstract exception type and is never even declared to be thrown (all declarations about this changed about 2 years ago). So places catching it should either change to catch SoyCompilationException, or do nothing and let it propagate.
Tested:
TAP sample presubmit queue
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=185050724