(maint) Do not error in validation exception handler

Previosuly if an unexpected type of error came through the document validator
it would itself raise a new exception and crash the Language Server.  This was
caused by the lack of a :line or :pos method on the exception or the inner
exception.  This commit changes the detection logic to ignore any exception that
does not contain line and position information in the exception object.  These
can be ignored as they are not Puppet manifest errors but a symptom of something
else.

lib/puppet-languageserver/document_validator.rb

@@ -88,18 +88,20 @@ def self.validate(content, workspace, _max_problems = 100)
           validation_environment.check_for_reparse
           validation_environment.known_resource_types.clear
         rescue StandardError => detail
-          # Somtimes the error is in the cause not the root object itself
-          detail = detail.cause if !detail.respond_to?(:line) && detail.respond_to?(:cause) && detail.cause.respond_to?(:line)
-
+          # Sometimes the error is in the cause not the root object itself
+          detail = detail.cause if !detail.respond_to?(:line) && detail.respond_to?(:cause)
+          ex_line = detail.respond_to?(:line) && !detail.line.nil? ? detail.line - 1 : nil # Line numbers from puppet exceptions are base 1
+          ex_pos = detail.respond_to?(:pos) && !detail.pos.nil? ? detail.pos : nil # Pos numbers from puppet are base 1
+
           message = detail.respond_to?(:message) ? detail.message : nil
           message = detail.basic_message if message.nil? && detail.respond_to?(:basic_message)
 
-          unless detail.line.nil? || detail.pos.nil? || message.nil?
+          unless ex_line.nil? || ex_pos.nil? || message.nil?
             result << LanguageServer::Diagnostic.create('severity' => LanguageServer::DIAGNOSTICSEVERITY_ERROR,
-                                                        'fromline' => detail.line - 1,  # Line numbers from puppet are base 1
-                                                        'toline' => detail.line - 1,    # Line numbers from puppet are base 1
-                                                        'fromchar' => detail.pos - 1,   # Pos numbers from puppet are base 1
-                                                        'tochar' => detail.pos + 1 - 1, # Pos numbers from puppet are base 1
+                                                        'fromline' => ex_line,
+                                                        'toline' => ex_line,
+                                                        'fromchar' => ex_pos,
+                                                        'tochar' => ex_pos + 1,
                                                         'source' => 'Puppet',
                                                         'message' => message)
           end