fix: Allow a DSN string.Empty to be overwritten by the environment

src/Sentry/Internal/SettingLocator.cs

@@ -33,16 +33,34 @@ public SettingLocator(SentryOptions options)
     public string GetDsn()
     {
         // For DSN only
-        // An empty string set on the option should NOT be converted to null because it is used
-        // to indicate the the SDK is disabled.
-        _options.Dsn ??= GetEnvironmentVariable(Constants.DsnEnvironmentVariable)
-                         ?? AssemblyForAttributes?.GetCustomAttribute<DsnAttribute>()?.Dsn;
+
+        // If the DSN has not been set at all require it to be on either the environment or an AssemblyAttribute. If
+        // neither can be found: throw
         if (_options.Dsn is null)
         {
-            throw new ArgumentNullException("You must supply a DSN to use Sentry." +
-                                            "To disable Sentry, pass an empty string: \"\"." +
-                                            "See https://docs.sentry.io/platforms/dotnet/configuration/options/#dsn");
+            _options.Dsn = GetEnvironmentVariable(Constants.DsnEnvironmentVariable)
+                           ?? AssemblyForAttributes?.GetCustomAttribute<DsnAttribute>()?.Dsn;
+
+            if (_options.Dsn is null)
+            {
+                throw new ArgumentNullException("You must supply a DSN to use Sentry." +
+                                                "To disable Sentry, pass an empty string: \"\"." +
+                                                "See https://docs.sentry.io/platforms/dotnet/configuration/options/#dsn");
+            }
+        }
+        // The SDK has been disabled by the user explicitly setting the DSN to `string.Empty`.
+        // By convention, the DSN can be overwritten in the environment
+        else if (_options.Dsn.Equals(string.Empty))
+        {
+            var dsn = GetEnvironmentVariable(Constants.DsnEnvironmentVariable)
+                           ?? AssemblyForAttributes?.GetCustomAttribute<DsnAttribute>()?.Dsn;
+
+            if (dsn is not null)
+            {
+                _options.Dsn = dsn;
+            }
         }
+
         return _options.Dsn;
     }