Fail louder in json2 if invalid data.

json-test/json2.py

@@ -58,13 +58,17 @@ def handle_int(xs: list[MatchObject]) -> list[int]:
 
     Note that this only works if adjacant joining is working.
     """
+    assert type(xs[0]) is str
     return [int(xs[0])]
 
 
 def _handle_exp(parts: list[MatchObject]) -> list[int]:
     """Convert the exponential part of a float to its integer value."""
-    total = force(__find('dig', parts)).matched[0]
+    dig = __find('dig', parts)
+    assert isinstance(dig, MatchCompound)
+    total = dig.matched[0]
     if sign := __find('sign', parts):
+        assert isinstance(sign, MatchCompound)
         if sign.matched[0][0] == '-':
             total *= -1
     return [total]
@@ -91,13 +95,16 @@ def _handle_number(parts: list[MatchObject]) -> list[float]:
     print(parts)
     # string: str = ''
     if base := __find('base', parts):
+        assert isinstance(base, MatchCompound)
         total += base.matched[0]
 
     if frac := __find('fractional', parts):
+        assert isinstance(frac, MatchCompound)
         d = frac.matched[0]
         total += d / 10**(math.floor(math.log10(d)) + 1)
 
     if exp := __find('exp', parts):
+        assert isinstance(exp, MatchCompound)
         total *= 10**exp.matched[0]
 
     if __find('minus', parts):