remove noexcept decls from ::getSingleOrEmpty

Summary: some weird heisenbug was triggered by these noexcept decls (see post for details)

Reviewed By: afrind

Differential Revision: D89935248

fbshipit-source-id: 62ee8ba78d452ea8be09c82a2338e84c55c8cc36

Author: hanidamlaj

third-party/proxygen/src/proxygen/lib/http/HTTPHeaders.cpp

@@ -364,12 +364,11 @@ HTTPHeaders::SingleOrNullptrResult HTTPHeaders::getSingleOrNullptr(
   return res;
 }
 
-const std::string& HTTPHeaders::getSingleOrEmpty(
-    HTTPHeaderCode code) const noexcept {
+const std::string& HTTPHeaders::getSingleOrEmpty(HTTPHeaderCode code) const {
   return *getSingleOrNullptr(code);
 }
 const std::string& HTTPHeaders::getSingleOrEmpty(
-    folly::StringPiece name) const noexcept {
+    folly::StringPiece name) const {
   return *getSingleOrNullptr(name);
 }
 

third-party/proxygen/src/proxygen/lib/http/HTTPHeaders.h

@@ -254,10 +254,9 @@ class HTTPHeaders {
    * only value under the given name. If either of these is violated, returns
    * empty_string.
    */
+  [[nodiscard]] const std::string& getSingleOrEmpty(HTTPHeaderCode code) const;
   [[nodiscard]] const std::string& getSingleOrEmpty(
-      HTTPHeaderCode code) const noexcept;
-  [[nodiscard]] const std::string& getSingleOrEmpty(
-      folly::StringPiece name) const noexcept;
+      folly::StringPiece name) const;
   [[nodiscard]] const std::string rawGet(const std::string& header) const {
     return getSingleOrEmpty(header);
   }