Simplify InitializeUri and remove some dead branches

Author: MihaZupan

src/libraries/System.Private.Uri/src/System/UriExt.cs

@@ -46,6 +46,16 @@ private void CreateThis(string? uri, bool dontEscape, UriKind uriKind, in UriCre
         private void InitializeUri(ParsingError err, UriKind uriKind, out UriFormatException? e)
         {
             DebugAssertInCtor();
+            Debug.Assert((err is ParsingError.None) == (_syntax is not null));
+
+            bool hasUnicode = false;
+
+            if (IriParsing && CheckForUnicodeOrEscapedUnreserved(_string))
+            {
+                _flags |= Flags.HasUnicode;
+                hasUnicode = true;
+                _originalUnicodeString = _string; // original string location changed
+            }
 
             if (err == ParsingError.None)
             {
@@ -80,26 +90,32 @@ private void InitializeUri(ParsingError err, UriKind uriKind, out UriFormatExcep
                     }
                 }
             }
-            else if (err > ParsingError.LastErrorOkayForRelativeUris)
+            else
+            {
+                // If we encountered any parsing errors that indicate this may be a relative Uri,
+                // and we'll allow relative Uri's, then create one.
+                if (err <= ParsingError.LastErrorOkayForRelativeUris)
+                {
+                    e = null;
+                    _flags &= Flags.UserEscaped | Flags.HasUnicode; // the only flags that makes sense for a relative uri
+                    if (hasUnicode)
+                    {
+                        // Iri'ze and then normalize relative uris
+                        _string = EscapeUnescapeIri(_originalUnicodeString, 0, _originalUnicodeString.Length, isQuery: false);
+                    }
+                }
+                else
                 {
                     // This is a fatal error based solely on scheme name parsing
                     _string = null!; // make it be invalid Uri
                     e = GetException(err);
-                return;
                 }
 
-            bool hasUnicode = false;
-
-            if (IriParsing && CheckForUnicodeOrEscapedUnreserved(_string))
-            {
-                _flags |= Flags.HasUnicode;
-                hasUnicode = true;
-                // switch internal strings
-                _originalUnicodeString = _string; // original string location changed
+                return;
             }
 
-            if (_syntax != null)
-            {
+            Debug.Assert(err == ParsingError.None && _syntax is not null);
+
             if (_syntax.IsSimple)
             {
                 if ((err = PrivateParseMinimal()) != ParsingError.None)
@@ -122,7 +138,6 @@ private void InitializeUri(ParsingError err, UriKind uriKind, out UriFormatExcep
                 }
                 else
                     e = null;
-                    // will return from here
 
                 if (e is null && hasUnicode)
                 {
@@ -148,18 +163,7 @@ private void InitializeUri(ParsingError err, UriKind uriKind, out UriFormatExcep
                 // Ask a registered type to validate this uri
                 _syntax.InternalValidate(this, out e);
 
-                    if (e != null)
-                    {
-                        // Can we still take it as a relative Uri?
-                        if (uriKind != UriKind.Absolute && err != ParsingError.None
-                            && err <= ParsingError.LastErrorOkayForRelativeUris)
-                        {
-                            _syntax = null!; // convert it to relative
-                            e = null;
-                            _flags &= Flags.UserEscaped; // the only flag that makes sense for a relative uri
-                        }
-                    }
-                    else // e == null
+                if (e is null)
                 {
                     if (err != ParsingError.None || InFact(Flags.ErrorOrParsingRecursion))
                     {
@@ -187,26 +191,6 @@ private void InitializeUri(ParsingError err, UriKind uriKind, out UriFormatExcep
                         }
                     }
                 }
-                    // will return from here
-                }
-            }
-            // If we encountered any parsing errors that indicate this may be a relative Uri,
-            // and we'll allow relative Uri's, then create one.
-            else if (err != ParsingError.None && uriKind != UriKind.Absolute
-                && err <= ParsingError.LastErrorOkayForRelativeUris)
-            {
-                e = null;
-                _flags &= (Flags.UserEscaped | Flags.HasUnicode); // the only flags that makes sense for a relative uri
-                if (hasUnicode)
-                {
-                    // Iri'ze and then normalize relative uris
-                    _string = EscapeUnescapeIri(_originalUnicodeString, 0, _originalUnicodeString.Length, isQuery: false);
-                }
-            }
-            else
-            {
-                _string = null!; // make it be invalid Uri
-                e = GetException(err);
             }
         }