datatable/java: Improve error messages

[mpkorstanje]

As reported in cucumber/cucumber-jvm#1928:

Given table1
  | aaa | bbb | ccc |

List<String> result1 = table1.asList(String.class);

As part of #540 this should have thrown an exception
but no exception was thrown. After fixing this, reviewing the
exceptions revealed that they were rather lacking in clarify. By
including all potential causes rather then a best guess we'll ensure
that all possible fixes have been suggested.

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).

Checklist:

• The change has been ported to Java.
• I've added tests for my code.
• I have updated the CHANGELOG accordingly.