Feature Request: Explicitly report bad connection in error messaging for getUpdateSql() / getInsertSql() / rs2html.

[NathanGibbs3]

Description

Noticed while working on #899 . The Error message states Connection or SQL invalid. It's ambiguous what the actual issue is. With some additional code we could separate the connection issue from the invalid SQL issue and return a more meaningful error message.

Environment

• ADOdb version: < 5.22.7
• Driver or Module: All
• Database type and version: All
• PHP version: All
• Platform: All

• I have tested that the problem is reproducible in the latest release / master branch / hotfix branch

Steps to reproduce

Detailed, step-by-step instructions to reproduce the behavior, including:

• code snippet
• SQL to create and populate database objects used by the code snippet

CREATE TABLE test ( test VARCHAR(255) );

Expected behavior

An explicit error message when the DB is not connected.

Additional context

See comment thread on #899
Depends on a fix for #994