Try to work around crash in function signature specialization

Author: DougGregor

Sources/SwiftOperators/OperatorTable.swift

@@ -42,6 +42,19 @@ public struct OperatorTable {
     }
   }
 
+  /// Initialize the operator precedence instance with a given set of
+  /// operators and precedence groups.
+  ///
+  /// If any error occurs, it will be thrown.
+  public init(
+    precedenceGroups: [PrecedenceGroup],
+    operators: [Operator]
+  ) throws {
+    try self.init(precedenceGroups: precedenceGroups, operators: operators) {
+      throw $0
+    }
+  }
+
   /// Record the operator in the given operator array.
   private func record(
     _ op: Operator,