diff --git a/apps/language_server/lib/language_server/dialyzer/success_typings.ex b/apps/language_server/lib/language_server/dialyzer/success_typings.ex
index 81e4825c2..a040b8313 100644
--- a/apps/language_server/lib/language_server/dialyzer/success_typings.ex
+++ b/apps/language_server/lib/language_server/dialyzer/success_typings.ex
@@ -14,7 +14,7 @@ defmodule ElixirLS.LanguageServer.Dialyzer.SuccessTypings do
         :dialyzer_plt.lookup_contract(plt, mfa) == :none,
         {stripped_fun, stripped_arity} = SourceFile.strip_macro_prefix({fun, arity}),
         line = SourceFile.function_line(mod, stripped_fun, stripped_arity),
-        is_integer(line),
+        is_integer(line) and line > 0,
         do: {file, line, {mod, stripped_fun, stripped_arity}, success_typing, stripped_fun != fun}
   end
 
diff --git a/apps/language_server/lib/language_server/providers/completion.ex b/apps/language_server/lib/language_server/providers/completion.ex
index 6df2e7bef..58485b515 100644
--- a/apps/language_server/lib/language_server/providers/completion.ex
+++ b/apps/language_server/lib/language_server/providers/completion.ex
@@ -1380,7 +1380,7 @@ defmodule ElixirLS.LanguageServer.Providers.Completion do
   defp sanitize_function_name(name, origin) when origin in ["Kernel", "Kernel.SpecialForms"],
     do: name
 
-  defp sanitize_function_name(name, origin) do
+  defp sanitize_function_name(name, _origin) do
     if not Regex.match?(~r/^([_\p{Ll}\p{Lo}][\p{L}\p{N}_]*[?!]?)$/u, name) do
       # not an allowed identifier - quote
       escaped =
diff --git a/apps/language_server/lib/language_server/providers/execute_command/apply_spec.ex b/apps/language_server/lib/language_server/providers/execute_command/apply_spec.ex
index 1ef581f99..bd42753ab 100644
--- a/apps/language_server/lib/language_server/providers/execute_command/apply_spec.ex
+++ b/apps/language_server/lib/language_server/providers/execute_command/apply_spec.ex
@@ -7,6 +7,7 @@ defmodule ElixirLS.LanguageServer.Providers.ExecuteCommand.ApplySpec do
   alias ElixirLS.LanguageServer.{JsonRpc, SourceFile}
   import ElixirLS.LanguageServer.Protocol
   alias ElixirLS.LanguageServer.Server
+  require Logger
 
   @behaviour ElixirLS.LanguageServer.Providers.ExecuteCommand
 
@@ -40,60 +41,68 @@ defmodule ElixirLS.LanguageServer.Providers.ExecuteCommand.ApplySpec do
       else
         new_line = SourceFile.function_line(mod, fun, arity)
 
-        if SourceFile.function_def_on_line?(cur_text, new_line, fun) do
+        if new_line != nil and new_line > 0 and
+             SourceFile.function_def_on_line?(cur_text, new_line, fun) do
           new_line
-        else
-          raise "Function definition has moved since suggestion was generated. " <>
-                  "Try again after file has been recompiled."
         end
       end
 
-    cur_line = Enum.at(SourceFile.lines(cur_text), line - 1)
-    [indentation] = Regex.run(~r/^\s*/u, cur_line)
-
-    # Attempt to format to fit within the preferred line length, fallback to having it all on one
-    # line if anything fails
-    formatted =
-      try do
-        target_line_length =
-          case SourceFile.formatter_for(uri, state.project_dir, true) do
-            {:ok, {_, opts, _formatter_exs_dir}} ->
-              Keyword.get(opts, :line_length, @default_target_line_length)
-
-            {:error, _} ->
-              @default_target_line_length
-          end
-
-        target_line_length = target_line_length - String.length(indentation)
-
-        Code.format_string!("@spec #{spec}", line_length: target_line_length)
-        |> IO.iodata_to_binary()
-        |> SourceFile.lines()
-        |> Enum.map_join("\n", &(indentation <> &1))
-        |> Kernel.<>("\n")
-      rescue
-        _ ->
-          "#{indentation}@spec #{spec}\n"
-      end
+    if line do
+      cur_line = Enum.at(SourceFile.lines(cur_text), line - 1)
+      [indentation] = Regex.run(~r/^\s*/u, cur_line)
+
+      # Attempt to format to fit within the preferred line length, fallback to having it all on one
+      # line if anything fails
+      formatted =
+        try do
+          target_line_length =
+            case SourceFile.formatter_for(uri, state.project_dir, true) do
+              {:ok, {_, opts, _formatter_exs_dir}} ->
+                Keyword.get(opts, :line_length, @default_target_line_length)
+
+              {:error, reason} ->
+                Logger.warning(
+                  "Unable to get formatter for #{uri} due to #{inspect(reason)}, using default line length"
+                )
+
+                @default_target_line_length
+            end
+
+          target_line_length = target_line_length - String.length(indentation)
+
+          Code.format_string!("@spec #{spec}", line_length: target_line_length)
+          |> IO.iodata_to_binary()
+          |> SourceFile.lines()
+          |> Enum.map_join("\n", &(indentation <> &1))
+          |> Kernel.<>("\n")
+        rescue
+          _ ->
+            "#{indentation}@spec #{spec}\n"
+        end
 
-    edit_result =
-      JsonRpc.send_request("workspace/applyEdit", %{
-        "label" => "Add @spec to #{mod}.#{fun}/#{arity}",
-        "edit" => %{
-          "changes" => %{
-            # we don't care about utf16 positions here as we send 0
-            uri => [%{"range" => range(line - 1, 0, line - 1, 0), "newText" => formatted}]
+      edit_result =
+        JsonRpc.send_request("workspace/applyEdit", %{
+          "label" => "Add @spec to #{mod}.#{fun}/#{arity}",
+          "edit" => %{
+            "changes" => %{
+              # we don't care about utf16 positions here as we send 0
+              uri => [%{"range" => range(line - 1, 0, line - 1, 0), "newText" => formatted}]
+            }
           }
-        }
-      })
+        })
 
-    case edit_result do
-      {:ok, %{"applied" => true}} ->
-        {:ok, nil}
+      case edit_result do
+        {:ok, %{"applied" => true}} ->
+          {:ok, nil}
 
-      other ->
-        {:error, :server_error,
-         "cannot insert spec, workspace/applyEdit returned #{inspect(other)}", true}
+        other ->
+          {:error, :server_error,
+           "cannot insert spec, workspace/applyEdit returned #{inspect(other)}", true}
+      end
+    else
+      {:error, :server_error,
+       "cannot insert spec, function definition has moved since suggestion was generated. " <>
+         "Try again after file has been recompiled.", false}
     end
   end
 end
diff --git a/apps/language_server/lib/language_server/providers/workspace_symbols.ex b/apps/language_server/lib/language_server/providers/workspace_symbols.ex
index a7a1e7d65..c5b45cfb4 100644
--- a/apps/language_server/lib/language_server/providers/workspace_symbols.ex
+++ b/apps/language_server/lib/language_server/providers/workspace_symbols.ex
@@ -276,11 +276,15 @@ defmodule ElixirLS.LanguageServer.Providers.WorkspaceSymbols do
   end
 
   defp find_function_location(module, function, arity, path) do
-    if String.ends_with?(path, ".erl") do
-      ErlangSourceFile.function_line(path, function)
-    else
-      SourceFile.function_line(module, function, arity)
-    end
+    line =
+      if String.ends_with?(path, ".erl") do
+        ErlangSourceFile.function_line(path, function)
+      else
+        SourceFile.function_line(module, function, arity)
+      end
+
+    # both functions can return nil
+    max(line || 1, 1)
   end
 
   defp find_module_path(module, beam_file) do