chore: recoverable panic in native functions (#732)

Fix #663

Some panic invoked in native functions should be recoverable from gno
code. To do that, `panic` is replaced with `machine.Panic()` which
checks first the call stack if there's a recover, before panic-ing.

gnovm/stdlibs/stdlibs.go

@@ -152,7 +152,8 @@ func InjectPackage(store gno.Store, pn *gno.PackageNode) {
 			func(m *gno.Machine) {
 				isOrigin := len(m.Frames) == 2
 				if !isOrigin {
-					panic("invalid non-origin call")
+					m.Panic(typedString("invalid non-origin call"))
+					return
 				}
 			},
 		)
@@ -314,13 +315,15 @@ func InjectPackage(store gno.Store, pn *gno.PackageNode) {
 				arg0 := m.LastBlock().GetParams1().TV
 				n := arg0.GetInt()
 				if n <= 0 {
-					panic("GetCallerAt requires positive arg")
+					m.Panic(typedString("GetCallerAt requires positive arg"))
+					return
 				}
 				if n > m.NumFrames() {
 					// NOTE: the last frame's LastPackage
 					// is set to the original non-frame
 					// package, so need this check.
-					panic("frame not found")
+					m.Panic(typedString("frame not found"))
+					return
 				}
 				var pkgAddr string
 				if n == m.NumFrames() {
@@ -426,7 +429,7 @@ func InjectPackage(store gno.Store, pn *gno.PackageNode) {
 				}
 				b32, err := bech32.ConvertAndEncode(prefix, bz)
 				if err != nil {
-					panic(err)
+					panic(err) // should not happen
 				}
 				res0 := gno.Go2GnoValue(
 					m.Alloc,

gnovm/tests/files/std10.gno

@@ -0,0 +1,14 @@
+package main
+
+import "std"
+
+func main() {
+	defer func() {
+		// assert panic is recoverable
+		println(recover())
+	}()
+	std.GetCallerAt(0)
+}
+
+// Output:
+// GetCallerAt requires positive arg

gnovm/tests/files/std11.gno

@@ -0,0 +1,14 @@
+package main
+
+import "std"
+
+func main() {
+	defer func() {
+		// assert panic is recoverable
+		println(recover())
+	}()
+	std.GetCallerAt(42)
+}
+
+// Output:
+// frame not found

gnovm/tests/files/std9.gno

@@ -0,0 +1,14 @@
+package main
+
+import "std"
+
+func main() {
+	defer func() {
+		// assert panic is recoverable
+		println(recover())
+	}()
+	std.AssertOriginCall()
+}
+
+// Output:
+// invalid non-origin call

gnovm/tests/imports.go

@@ -485,6 +485,7 @@ func testPackageInjector(store gno.Store, pn *gno.PackageNode) {
 			func(m *gno.Machine) {
 				if !isOriginCall(m) {
 					m.Panic(typedString("invalid non-origin call"))
+					return
 				}
 			},
 		)
@@ -515,13 +516,15 @@ func testPackageInjector(store gno.Store, pn *gno.PackageNode) {
 				arg0 := m.LastBlock().GetParams1().TV
 				n := arg0.GetInt()
 				if n <= 0 {
-					panic("GetCallerAt requires positive arg")
+					m.Panic(typedString("GetCallerAt requires positive arg"))
+					return
 				}
 				if n > m.NumFrames()-1 {
 					// NOTE: the last frame's LastPackage
 					// is set to the original non-frame
 					// package, so need this check.
-					panic("frame not found")
+					m.Panic(typedString("frame not found"))
+					return
 				}
 				var pkgAddr string
 				if n == m.NumFrames()-1 {