In trying to come up for some reason behind issue #6365 (which only
happens on some platforms) the best guess is that some components are
managing to get a string value all the way up to the Polymer UI for
temperature, which then an increment of +0.5 is treating as a string
concat operation instead of addition. So 20 + 0.5 becomes 200.5 hits
the max thermostat value.
This will throw an exception if the climate temp value isn't a
number. That's going to turn a soft fail into a hard fail on
potentially a number of platforms. Mysensors is one of the platforms
that was reported as having the issue. So put some explicit float
casts where that might be coming from as well.
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