Parse a lead-sheet chord symbol, reporting failure instead of throwing it.
The same reading as parseChordSymbol — that function is this one with
its error thrown — for the callers where a symbol that does not parse yet is
the normal state of the input rather than a fault: a chord field says what is
wrong with what has been typed so far, and does not need a try around every
keystroke to do it.
Parse a lead-sheet chord symbol, reporting failure instead of throwing it.
The same reading as parseChordSymbol — that function is this one with its error thrown — for the callers where a symbol that does not parse yet is the normal state of the input rather than a fault: a chord field says what is wrong with what has been typed so far, and does not need a
tryaround every keystroke to do it.