Add `error` to the `RescuedExceptionsVariableName#allowed_names`

spec/ameba/rule/naming/rescued_exceptions_variable_name_spec.cr

@@ -21,7 +21,7 @@ module Ameba::Rule::Naming
         def foo
           raise "foo"
         rescue wtf
-        # ^^^^^^^^ error: Disallowed variable name, use one of these instead: 'e', 'ex', 'exception'
+        # ^^^^^^^^ error: Disallowed variable name, use one of these instead: 'e', 'ex', 'exception', 'error'
           nil
         end
         CRYSTAL
@@ -31,7 +31,7 @@ module Ameba::Rule::Naming
       context "#allowed_names" do
         it "returns sensible defaults" do
           rule = RescuedExceptionsVariableName.new
-          rule.allowed_names.should eq %w[e ex exception]
+          rule.allowed_names.should eq %w[e ex exception error]
         end
 
         it "allows setting custom names" do

src/ameba/rule/naming/rescued_exceptions_variable_name.cr

@@ -22,12 +22,12 @@ module Ameba::Rule::Naming
   # ```
   # Naming/RescuedExceptionsVariableName:
   #   Enabled: true
-  #   AllowedNames: [e, ex, exception]
+  #   AllowedNames: [e, ex, exception, error]
   # ```
   class RescuedExceptionsVariableName < Base
     properties do
       description "Makes sure that rescued exceptions variables are named as expected"
-      allowed_names %w[e ex exception]
+      allowed_names %w[e ex exception error]
     end
 
     MSG          = "Disallowed variable name, use one of these instead: '%s'"