patch 9.0.2146: text-property without type errors when joining

patch 9.0.2146: text-property without type errors when joining

Problem:  text-property without type errors when joining
Solution: count all text-properties, with or without type
          before joining lines

Error when joining lines with text properties without a proper type

When joining lines, we need to consider all text properties that are
attached to a line, even when those text properties are invalid and do
not have a type attached to them.

However, since patch v9.0.0993
(commit: 89469d157aea01513bde826b4519dd6b5fbceae4)
those text properties won't be counted when joining lines and therefore
this will cause the adjustment for text properties on joining to go
wrong (and may later cause SIGABRT with an invalid free pointer)

I am not sure, why the condition to not count text properties with a
valid type was added in patch v9.0.993, because no test fails if those
condition is removed. So let's just remove this condition and add a test
that verifies, that we are able to join lines, even when the text
properties attached to it do not have a valid type.

fixes: #13609
closes: #13614

Signed-off-by: Christian Brabandt <cb@256bit.org>