inspect terms that otherwise can't be serialized by exporter (#40)

instrumentation/opentelemetry_phoenix/lib/opentelemetry_phoenix/reason.ex

@@ -26,27 +26,27 @@ defmodule OpentelemetryPhoenix.Reason do
 
   def normalize({:badarity, {fun, args}}) do
     {:arity, arity} = Function.info(fun, :arity)
-    [reason: :badarity, function: "#{inspect(fun)}", arity: arity, args: args]
+    [reason: :badarity, function: _inspect(fun), arity: arity, args: _inspect(args)]
   end
 
   def normalize({:badfun, term}) do
-    [reason: :badfun, term: term]
+    [reason: :badfun, term: _inspect(term)]
   end
 
   def normalize({:badstruct, struct, term}) do
-    [reason: :badstruct, struct: struct, term: term]
+    [reason: :badstruct, struct: struct, term: _inspect(term)]
   end
 
   def normalize({:badmatch, term}) do
-    [reason: :badmatch, term: term]
+    [reason: :badmatch, term: _inspect(term)]
   end
 
   def normalize({:badmap, term}) do
-    [reason: :badmap, term: term]
+    [reason: :badmap, term: _inspect(term)]
   end
 
   def normalize({:badbool, op, term}) do
-    [reason: :badbool, operator: op, term: term]
+    [reason: :badbool, operator: op, term: _inspect(term)]
   end
 
   def normalize({:badkey, key}) do
@@ -54,23 +54,23 @@ defmodule OpentelemetryPhoenix.Reason do
   end
 
   def normalize({:badkey, key, map}) do
-    [reason: :badkey, key: key, map: map]
+    [reason: :badkey, key: key, map: _inspect(map)]
   end
 
   def normalize({:case_clause, term}) do
-    [reason: :case_clause, term: term]
+    [reason: :case_clause, term: _inspect(term)]
   end
 
   def normalize({:with_clause, term}) do
-    [reason: :with_clause, term: term]
+    [reason: :with_clause, term: _inspect(term)]
   end
 
   def normalize({:try_clause, term}) do
-    [reason: :try_clause, term: term]
+    [reason: :try_clause, term: _inspect(term)]
   end
 
   def normalize({:badarg, payload}) do
-    [reason: :badarg, payload: payload]
+    [reason: :badarg, payload: _inspect(payload)]
   end
 
   def normalize(other) do
@@ -80,4 +80,12 @@ defmodule OpentelemetryPhoenix.Reason do
   def normalize(other, _stacktrace) do
     [reason: other]
   end
+
+  defp _inspect(term) do
+    if String.Chars.impl_for(term) do
+      term
+    else
+      inspect(term)
+    end
+  end
 end

instrumentation/opentelemetry_phoenix/test/opentelemetry_phoenix_test.exs

@@ -140,7 +140,7 @@ defmodule OpentelemetryPhoenixTest do
                             {"exception.message", "Erlang error: :badkey"},
                             {"exception.stacktrace", _stacktrace},
                             {:key, :name},
-                            {:map, %{username: "rick"}}
+                            {:map, "%{username: \"rick\"}"}
                           ]
                         )
                       ],