Solve mypy errors.

[knutnergaard]

Continuation of #776.

Remaining errors to be collected in #775:

glyph.py:85: error: Signature of "_reprContents" incompatible with supertype "BaseObject"  [override]
glyph.py:85: note:      Superclass:
glyph.py:85: note:          @classmethod
glyph.py:85: note:          def _reprContents(cls) -> List[str]
glyph.py:85: note:      Subclass:
glyph.py:85: note:          def _reprContents(self) -> List[str]
glyph.py:2790: error: Signature of "isCompatible" incompatible with supertype "InterpolationMixin"  [override]
glyph.py:2790: note:      Superclass:
glyph.py:2790: note:          def isCompatible(self, other: Any, cls: Type[Any]) -> Tuple[bool, Any]
glyph.py:2790: note:      Subclass:
glyph.py:2790: note:          def isCompatible(self, other: BaseGlyph) -> Tuple[bool, str]

[knutnergaard]

@benkiel Not sure what's wrong here.
Are the margin setters value type supposed to be Optional[IntFloatType], same as the margin getters return type?

[benkiel]

@knutnergaard no, setters should not allow None, getters may return that: a glyph with no outlines will not have margins

[knutnergaard]

@benkiel OK, then is it possible that the tests for the margins properties should be updated?

Since e.g., normalizeGlyphBottomMargin allows -> Optional[IntFloatType] (i.e., int, float and None), mypy is complaining that set_base_bottomMargin potentially passes None to set_bottomMargin, which only allows IntFloatType. Unfortunately, when attempting to eliminate None before the call to set_bottomMargin, the test fails.

Hopefully that made sense.

[knutnergaard]

Solved.

[benkiel]

@knutnergaard I'm trying to work out why this change made things fail initially...

[benkiel]

Figured it out: type error was thrown in the math part, but I see where mypy got grumpy with that. Change has the nice effect of a better error message!