This adapts an idea of James Harkins' PnNilSafe (ddwPatterns quark) for Psym. If all patterns in the Dictinonary return nil, then Psym's embedInStream can produce an infinite loop, as it never yields. PnNilSafe can't be wrapped around Psym, but the check with logical time can be built into Psym itself. The wrapping into PsymNilSafe can shortly be written by applying Pattern: -symplay instead of Pattern: -play. See PLx_and_live_coding_with_Strings for more examples.
Creates a new PsymNilSafe object. pattern expects a pattern of Symbols, dict the lookup dictionary and defaults to the current Environment. maxNull is the number of events with delta = 0 after which PsymNilSafe's method 'embedInStream' yields and thus stops a potentially endless loop. maxNull defaults to 128.
Getter and setter for PsymNilSafe's variable maxNull.