Do not bail out if a required tool is not found
Do not bail out if a required tool is not found

Previously a NullPointer exception was thrown.
Now the build go on and fails when the recipe cannot be replaced
the correct tool path, that is a much more informative error.

me-no-dev/Arduino-1,stickbreaker/Arduino,me-no-dev/Arduino-1,bsmr-arduino/Arduino,PaoloP74/Arduino,Chris--A/Arduino,PaoloP74/Arduino,nandojve/Arduino,nandojve/Arduino,stickbreaker/Arduino,PaoloP74/Arduino,majenkotech/Arduino,Chris--A/Arduino,PaoloP74/Arduino,nandojve/Arduino,nandojve/Arduino,majenkotech/Arduino,majenkotech/Arduino,me-no-dev/Arduino-1,Chris--A/Arduino,me-no-dev/Arduino-1,me-no-dev/Arduino-1,stickbreaker/Arduino,nandojve/Arduino,nandojve/Arduino,bsmr-arduino/Arduino,PaoloP74/Arduino,bsmr-arduino/Arduino,Chris--A/Arduino,majenkotech/Arduino,nandojve/Arduino,bsmr-arduino/Arduino,Chris--A/Arduino,me-no-dev/Arduino-1,nandojve/Arduino,majenkotech/Arduino,bsmr-arduino/Arduino,Chris--A/Arduino,bsmr-arduino/Arduino,PaoloP74/Arduino,stickbreaker/Arduino,PaoloP74/Arduino,stickbreaker/Arduino,bsmr-arduino/Arduino,majenkotech/Arduino,Chris--A/Arduino,me-no-dev/Arduino-1,bsmr-arduino/Arduino,Chris--A/Arduino,PaoloP74/Arduino,majenkotech/Arduino,stickbreaker/Arduino,stickbreaker/Arduino,me-no-dev/Arduino-1