Handle strand creation for erroneous self-payment

src/ripple/app/paths/RippleCalc.cpp

@@ -147,7 +147,7 @@ RippleCalc::Output RippleCalc::rippleCalculate (
         }
         catch (std::exception& e)
         {
-            JLOG (j.trace()) << "Exception from flow" << e.what ();
+            JLOG (j.error()) << "Exception from flow: " << e.what ();
             if (!useFlowV1Output)
                 Rethrow();
         }

src/ripple/app/paths/impl/PaySteps.cpp

@@ -101,7 +101,7 @@ toStep (
     if (e1->isOffer() && e2->isAccount())
     {
         // should already be taken care of
-        JLOG (j.warn())
+        JLOG (j.error())
             << "Found offer/account payment step. Aborting payment strand.";
         assert (0);
         if (ctx.view.rules().enabled(fix1373))
@@ -498,6 +498,9 @@ toStrandV2 (
         }
     }
 
+    if (normPath.size() < 2)
+        return {temBAD_PATH, Strand{}};
+
     auto const strandSrc = normPath.front().getAccountID ();
     auto const strandDst = normPath.back().getAccountID ();
     bool const isDefaultPath = path.empty();

src/test/app/Flow_test.cpp

@@ -1235,7 +1235,23 @@ struct Flow_test : public beast::unit_test::suite
              sendmax (drops(20000000000)), txflags (tfPartialPayment));
     }
 
+    void
+    testEmptyStrand(std::initializer_list<uint256> fs)
+    {
+        testcase("Empty Strand");
+        using namespace jtx;
 
+        auto const alice = Account("alice");
+
+        Env env(*this, features(fs));
+
+        env.fund(XRP(10000), alice);
+
+        env(pay(alice, alice,
+                alice["USD"](100)),
+            path(~alice["USD"]),
+            ter(temBAD_PATH));
+    }
 
     void run() override
     {
@@ -1269,6 +1285,7 @@ struct Flow_test : public beast::unit_test::suite
         testWithFeats(featureFlow);
         testWithFeats(featureFlow, fix1373);
         testWithFeats(featureFlow, fix1373, featureFlowCross);
+        testEmptyStrand({featureFlow, fix1373, featureFlowCross});
     }
 };