fix: use correct Ruby exceptions:

- StandardError for most exceptions
- Unleash::Strategy::NotImplemented should extend RuntimeError

lib/unleash/client.rb

@@ -136,7 +136,7 @@ def register
       # Send the request, if possible
       begin
         response = http_send_request(info.to_json)
-      rescue Exception => e
+      rescue StandardError => e
         Unleash.logger.error "unable to register client with unleash server due to exception #{e.class}:'#{e}'."
         Unleash.logger.error "stacktrace: #{e.backtrace}"
       end

lib/unleash/scheduled_executor.rb

@@ -52,7 +52,7 @@ def run_blk(blk)
 
       yield(*blk)
       self.retry_count = 0
-    rescue Exception => e
+    rescue StandardError => e
       self.retry_count += 1
       Unleash.logger.error "thread #{name} threw exception #{e.class} " \
           " (#{self.retry_count}/#{self.max_exceptions}): '#{e}'"

lib/unleash/strategy/base.rb

@@ -1,6 +1,6 @@
 module Unleash
   module Strategy
-    class NotImplemented < Exception
+    class NotImplemented < RuntimeError
     end
 
     class Base

lib/unleash/toggle_fetcher.rb

@@ -16,7 +16,7 @@ def initialize
       # start by fetching synchronously, and failing back to reading the backup file.
       begin
         fetch
-      rescue Exception => e
+      rescue StandardError => e
         Unleash.logger.warn "ToggleFetcher was unable to fetch from the network, attempting to read from backup file."
         Unleash.logger.debug "Exception Caught: #{e}"
         read!
@@ -73,7 +73,7 @@ def save!
           file.write(self.toggle_cache.to_json)
           File.rename(backup_file_tmp, backup_file)
         end
-      rescue Exception => e
+      rescue StandardError => e
         # This is not really the end of the world. Swallowing the exception.
         Unleash.logger.error "Unable to save backup file. Exception thrown #{e.class}:'#{e}'"
         Unleash.logger.error "stacktrace: #{e.backtrace}"
@@ -139,7 +139,7 @@ def read!
         Unleash.logger.error "Unable to read the backup_file: #{e}"
       rescue JSON::ParserError => e
         Unleash.logger.error "Unable to parse JSON from existing backup_file: #{e}"
-      rescue Exception => e
+      rescue StandardError => e
         Unleash.logger.error "Unable to extract valid data from backup_file. Exception thrown: #{e}"
       ensure
         file&.close