Flat String creation failing where it worked reliably before

Wed 2019.01.30

Now peppered with the actual address as seen by allocation:

[L270] nArySizeRGB 180
strg typeof: string len: 256
Free: 1375
addr: 536955892
strd typeof: string len: 180
Free: 1361
addr: 536954404
Uncaught Error: Cannot read property 'length' of undefined
 at line 4 col 228
..."+typeof strr+" len: "+strr.length);console.log("Free: "+pro...

>pm()
{ "free": 1467, "usage": 3633, "total": 5100, "history": 1330,
  "gc": 0, "gctime": 7.30037689208, "stackEndAddress": 536958216, "flash_start": 134217728, "flash_binary_end": 376936,
  "flash_code_start": 134234112, "flash_length": 393216 }

stackEndAddress: 536958216 - actual strg: 536955892 = 2324

Free: 1375 - 1361 = 14     14 blocks * 16 = 224 bytes used

strg: 536955892 - strd: 536954404 = 1488

There should be 93 blocks of stack remaining  93 == 1488 / 16 bytes per JsVar

String strr isn't created as it appears to run into/off the end of the stack.

So, either; using process.memory().free to determine what memory is available isn't the best way or doesn't determine correctly the actual memory (unlikely as it's been around for some time) available or
the way in which flat string memory is allocated needs to be re-visited perhaps?