Initialize ojdbc_jars before require so LoadError rescue never crashes

If require "java" or require "jruby" raises LoadError, the rescue
block below previously referenced the unbound local ojdbc_jars and
would itself raise NameError, masking the original error. Hoist the
empty-array initialization above the begin so the rescue path always
has a safe value to interpolate.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: yahonda

lib/plsql/jdbc_connection.rb

@@ -1,3 +1,5 @@
+ojdbc_jars = []
+
 begin
   require "java"
   require "jruby"
@@ -11,7 +13,6 @@
     java_version.to_i
   end
 
-  ojdbc_jars = []
   ojdbc_jars << "ojdbc17.jar" if java_major >= 17
   ojdbc_jars << "ojdbc11.jar" if java_major >= 11
   ojdbc_jars << "ojdbc8.jar"  if java_major >= 8