Avoid one-letter names if possible

src/ameba/formatter/disabled_formatter.cr

@@ -5,11 +5,11 @@ module Ameba::Formatter
       output << "Disabled rules using inline directives: \n\n"
 
       sources.each do |source|
-        source.issues.select(&.disabled?).each do |e|
+        source.issues.select(&.disabled?).each do |issue|
-          next unless loc = e.location
+          next unless loc = issue.location
 
           output << "#{source.path}:#{loc.line_number}".colorize(:cyan)
-          output << " #{e.rule.name}\n"
+          output << " #{issue.rule.name}\n"
         end
       end
     end

src/ameba/formatter/flycheck_formatter.cr

@@ -3,16 +3,16 @@ module Ameba::Formatter
     @mutex = Mutex.new
 
     def source_finished(source : Source)
-      source.issues.each do |e|
+      source.issues.each do |issue|
-        next if e.disabled?
+        next if issue.disabled?
-        next if e.correctable? && config[:autocorrect]?
+        next if issue.correctable? && config[:autocorrect]?
 
-        next unless loc = e.location
+        next unless loc = issue.location
 
         @mutex.synchronize do
           output.printf "%s:%d:%d: %s: [%s] %s\n",
-            source.path, loc.line_number, loc.column_number, e.rule.severity.symbol,
+            source.path, loc.line_number, loc.column_number, issue.rule.severity.symbol,
-            e.rule.name, e.message.gsub('\n', " ")
+            issue.rule.name, issue.message.gsub('\n', " ")
         end
       end
     end

src/ameba/rule/lint/literal_in_interpolation.cr

@@ -26,8 +26,8 @@ module Ameba::Rule::Lint
 
     def test(source, node : Crystal::StringInterpolation)
       node.expressions
-        .select { |e| !e.is_a?(Crystal::StringLiteral) && literal?(e) }
+        .select { |exp| !exp.is_a?(Crystal::StringLiteral) && literal?(exp) }
-        .each { |n| issue_for n, MSG }
+        .each { |exp| issue_for exp, MSG }
     end
   end
 end

src/ameba/rule/lint/redundant_string_coercion.cr

@@ -36,12 +36,12 @@ module Ameba::Rule::Lint
     end
 
     private def string_coercion_nodes(node)
-      node.expressions.select do |e|
+      node.expressions.select do |exp|
-        e.is_a?(Crystal::Call) &&
+        exp.is_a?(Crystal::Call) &&
-          e.name == "to_s" &&
+          exp.name == "to_s" &&
-          e.args.size.zero? &&
+          exp.args.size.zero? &&
-          e.named_args.nil? &&
+          exp.named_args.nil? &&
-          e.obj
+          exp.obj
       end
     end
   end

src/ameba/rule/style/negated_conditions_in_unless.cr

@@ -42,7 +42,7 @@ module Ameba::Rule::Style
       when Crystal::BinaryOp
         negated_condition?(node.left) || negated_condition?(node.right)
       when Crystal::Expressions
-        node.expressions.any? { |e| negated_condition?(e) }
+        node.expressions.any? { |exp| negated_condition?(exp) }
       when Crystal::Not
         true
       else