Fixed issues with parsing METARS that could cause an ifinite loop crash and misinterpreted units#528
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apps4av
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Apr 24, 2026
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Previously, parseData() prevented parsing past the last token by not incrementing the index if it was already on the last token, which could lead to getting stuck in an infinite loop if the last token was a runway visual range group, a weather group, or a sky condition, eventually leading to a crash. This was fixed by unconditionally incrementing the index and then conditionally returning from the function if there were no more tokens to parse. This also fixed an oversight where the parser previously assumed non-empty METARS would have at least 3 tokens which could lead to indexing past the last token and causing an exception on missing/delayed METARS which may have their LocID or Time fields set to "NIL=" according to the GDL90 specification.
A sample of a problematic METAR that this fixes is as follows
METAR KMER 242355Z 35013KT 10SM CLR=
Additionally, the trailing '=' that may be included as an optional message delimiter would remain on the last token, which could cause unit detection using String.endsWith() to select the wrong units. This was fixed by removing the trailing '=' from the data string before parsing.