diff --git a/convex-cli/GENESIS.md b/convex-cli/GENESIS.md
index d0aa6aaee..0462319ef 100644
--- a/convex-cli/GENESIS.md
+++ b/convex-cli/GENESIS.md
@@ -40,3 +40,26 @@ alias convex="java -jar ~/convex.jar"
 ### Upload keystore
 
 
+
+
+### Managing with screen
+
+Start screen session
+
+```
+screen
+```
+
+Run peer
+
+```
+convex peer start
+```
+
+Detach with Ctrl-a + Ctrl-d 
+
+Back to screen with:
+
+```
+screen -r
+```
\ No newline at end of file
diff --git a/convex-core/src/main/java/convex/core/cvm/ops/Invoke.java b/convex-core/src/main/java/convex/core/cvm/ops/Invoke.java
index 2f707cb65..5869895b9 100644
--- a/convex-core/src/main/java/convex/core/cvm/ops/Invoke.java
+++ b/convex-core/src/main/java/convex/core/cvm/ops/Invoke.java
@@ -102,8 +102,11 @@ public Context execute(Context context) {
 		// Specific check for an error so we can add stack trace info
 		if (ctx.isError()) {
 			// getError()must be non-null at this point
-			
-			ctx.getError().addTrace("In expression: "+RT.print(this));
+			try {
+			   ctx.getError().addTrace("In expression: "+RT.print(this));
+			} catch (Exception e) {
+			   ctx.getError().addTrace("TRACE FAILED");
+			}
 		}
 
 		return ctx;
diff --git a/convex-core/src/main/java/convex/core/lang/impl/MultiFn.java b/convex-core/src/main/java/convex/core/lang/impl/MultiFn.java
index 0491f47ee..d520a86f8 100644
--- a/convex-core/src/main/java/convex/core/lang/impl/MultiFn.java
+++ b/convex-core/src/main/java/convex/core/lang/impl/MultiFn.java
@@ -53,10 +53,15 @@ public boolean printInternal(BlobBuilder bb, long limit) {
 		AVector<AClosure<T>> fns=getFunctions();
 		for (long i=0; i<num; i++) {
 			if (i>0) bb.append(' ');
-			bb.append('(');
 			AClosure<?> fn=Fn.ensureFunction(fns.get(i));
-			if (!fn.printInternal(bb,limit)) return false;;
-			bb.append(')');
+			if (fn==null) {
+				bb.append("nil");
+				if (!bb.check(limit)) return false;
+			} else {
+				bb.append('(');
+				if (!fn.printInternal(bb,limit)) return false;
+				bb.append(')');
+			}
 		}
 		return bb.check(limit);
 	}