RFR: 8326915: NPE when a validating parser is restricted [v2]

[Joe Wang]

> Fix a NPE when a validating parser is restricted by the JDKCatalog resolve property. Also slightly improved the error msg with the catalog name.
> 
> Test: new test added
>          existing test CatalogSupport5 would fail without the Null check on ErrorReporter. It's a separate issue not covered by this fix.

Joe Wang has updated the pull request incrementally with one additional commit since the last revision:

  input.substring second argument not needed; proper test method name

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/18071/files
  - new: https://git.openjdk.org/jdk/pull/18071/files/6efb3c22..d847cf5d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18071&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18071&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/18071.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18071/head:pull/18071

PR: https://git.openjdk.org/jdk/pull/18071