7 files changed, 35 insertions, 8 deletions
diff --git a/scene/resources/font.cpp b/scene/resources/font.cpp
index b4773adc6f..702f2ed1c8 100644
--- a/scene/resources/font.cpp
+++ b/scene/resources/font.cpp
@@ -828,6 +828,8 @@ Size2 Font::get_multiline_string_size(const String &p_text, float p_width, int p
 }
 
 void Font::draw_string(RID p_canvas_item, const Point2 &p_pos, const String &p_text, HAlign p_align, float p_width, int p_size, const Color &p_modulate, int p_outline_size, const Color &p_outline_modulate, uint8_t p_flags) const {
+	ERR_FAIL_COND(data.is_empty());
+
 	uint64_t hash = p_text.hash64();
 	hash = hash_djb2_one_64(p_size, hash);
 
@@ -858,6 +860,8 @@ void Font::draw_string(RID p_canvas_item, const Point2 &p_pos, const String &p_t
 }
 
 void Font::draw_multiline_string(RID p_canvas_item, const Point2 &p_pos, const String &p_text, HAlign p_align, float p_width, int p_max_lines, int p_size, const Color &p_modulate, int p_outline_size, const Color &p_outline_modulate, uint8_t p_flags) const {
+	ERR_FAIL_COND(data.is_empty());
+
 	uint64_t hash = p_text.hash64();
 	hash = hash_djb2_one_64(p_size, hash);
 
diff --git a/scene/resources/style_box.cpp b/scene/resources/style_box.cpp
index 8e47c1c15c..9b80224c3f 100644
--- a/scene/resources/style_box.cpp
+++ b/scene/resources/style_box.cpp
@@ -937,8 +937,17 @@ void StyleBoxLine::_bind_methods() {
 }
 
 float StyleBoxLine::get_style_margin(Side p_side) const {
-	ERR_FAIL_INDEX_V((int)p_side, 4, thickness);
-	return thickness;
+	ERR_FAIL_INDEX_V((int)p_side, 4, 0);
+
+	if (vertical) {
+		if (p_side == SIDE_LEFT || p_side == SIDE_RIGHT) {
+			return thickness / 2.0;
+		}
+	} else if (p_side == SIDE_TOP || p_side == SIDE_BOTTOM) {
+		return thickness / 2.0;
+	}
+
+	return 0;
 }
 
 Size2 StyleBoxLine::get_center_size() const {
diff --git a/scene/resources/surface_tool.cpp b/scene/resources/surface_tool.cpp
index 5ce3532d42..47933bd69a 100644
--- a/scene/resources/surface_tool.cpp
+++ b/scene/resources/surface_tool.cpp
@@ -299,6 +299,7 @@ void SurfaceTool::add_triangle_fan(const Vector<Vector3> &p_vertices, const Vect
 
 void SurfaceTool::add_index(int p_index) {
 	ERR_FAIL_COND(!begun);
+	ERR_FAIL_COND(p_index < 0);
 
 	format |= Mesh::ARRAY_FORMAT_INDEX;
 	index_array.push_back(p_index);
diff --git a/scene/resources/text_line.cpp b/scene/resources/text_line.cpp
index ed69c093cf..925867a1f2 100644
--- a/scene/resources/text_line.cpp
+++ b/scene/resources/text_line.cpp
@@ -167,6 +167,7 @@ void TextLine::set_bidi_override(const Vector<Vector2i> &p_override) {
 }
 
 bool TextLine::add_string(const String &p_text, const Ref<Font> &p_fonts, int p_size, const Dictionary &p_opentype_features, const String &p_language) {
+	ERR_FAIL_COND_V(p_fonts.is_null(), false);
 	bool res = TS->shaped_text_add_string(rid, p_text, p_fonts->get_rids(), p_size, p_opentype_features, p_language);
 	spacing_top = p_fonts->get_spacing(Font::SPACING_TOP);
 	spacing_bottom = p_fonts->get_spacing(Font::SPACING_BOTTOM);
diff --git a/scene/resources/text_paragraph.cpp b/scene/resources/text_paragraph.cpp
index 94957df510..444a4bb22a 100644
--- a/scene/resources/text_paragraph.cpp
+++ b/scene/resources/text_paragraph.cpp
@@ -243,6 +243,7 @@ TextServer::Orientation TextParagraph::get_orientation() const {
 }
 
 bool TextParagraph::set_dropcap(const String &p_text, const Ref<Font> &p_fonts, int p_size, const Rect2 &p_dropcap_margins, const Dictionary &p_opentype_features, const String &p_language) {
+	ERR_FAIL_COND_V(p_fonts.is_null(), false);
 	TS->shaped_text_clear(dropcap_rid);
 	dropcap_margins = p_dropcap_margins;
 	bool res = TS->shaped_text_add_string(dropcap_rid, p_text, p_fonts->get_rids(), p_size, p_opentype_features, p_language);
@@ -257,6 +258,7 @@ void TextParagraph::clear_dropcap() {
 }
 
 bool TextParagraph::add_string(const String &p_text, const Ref<Font> &p_fonts, int p_size, const Dictionary &p_opentype_features, const String &p_language) {
+	ERR_FAIL_COND_V(p_fonts.is_null(), false);
 	bool res = TS->shaped_text_add_string(rid, p_text, p_fonts->get_rids(), p_size, p_opentype_features, p_language);
 	spacing_top = p_fonts->get_spacing(Font::SPACING_TOP);
 	spacing_bottom = p_fonts->get_spacing(Font::SPACING_BOTTOM);
diff --git a/scene/resources/visual_shader.cpp b/scene/resources/visual_shader.cpp
index 438e130cf4..859546694f 100644
--- a/scene/resources/visual_shader.cpp
+++ b/scene/resources/visual_shader.cpp
@@ -585,6 +585,12 @@ bool VisualShader::is_port_types_compatible(int p_a, int p_b) const {
 void VisualShader::connect_nodes_forced(Type p_type, int p_from_node, int p_from_port, int p_to_node, int p_to_port) {
 	ERR_FAIL_INDEX(p_type, TYPE_MAX);
 	Graph *g = &graph[p_type];
+
+	ERR_FAIL_COND(!g->nodes.has(p_from_node));
+	ERR_FAIL_INDEX(p_from_port, g->nodes[p_from_node].node->get_output_port_count());
+	ERR_FAIL_COND(!g->nodes.has(p_to_node));
+	ERR_FAIL_INDEX(p_to_port, g->nodes[p_to_node].node->get_input_port_count());
+
 	Connection c;
 	c.from_node = p_from_node;
 	c.from_port = p_from_port;
@@ -675,6 +681,8 @@ void VisualShader::get_node_connections(Type p_type, List<Connection> *r_connect
 }
 
 void VisualShader::set_mode(Mode p_mode) {
+	ERR_FAIL_INDEX_MSG(p_mode, Mode::MODE_MAX, vformat("Invalid shader mode: %d.", p_mode));
+
 	if (shader_mode == p_mode) {
 		return;
 	}
@@ -1398,11 +1406,11 @@ bool VisualShader::has_func_name(RenderingServer::ShaderMode p_mode, const Strin
 }
 
 void VisualShader::_update_shader() const {
-	if (!dirty) {
+	if (!dirty.is_set()) {
 		return;
 	}
 
-	dirty = false;
+	dirty.clear();
 
 	StringBuilder global_code;
 	StringBuilder global_code_per_node;
@@ -1588,11 +1596,11 @@ void VisualShader::_update_shader() const {
 }
 
 void VisualShader::_queue_update() {
-	if (dirty) {
+	if (dirty.is_set()) {
 		return;
 	}
 
-	dirty = true;
+	dirty.set();
 	call_deferred("_update_shader");
 }
 
@@ -1612,7 +1620,7 @@ void VisualShader::_input_type_changed(Type p_type, int p_id) {
 }
 
 void VisualShader::rebuild() {
-	dirty = true;
+	dirty.set();
 	_update_shader();
 }
 
@@ -1666,6 +1674,7 @@ void VisualShader::_bind_methods() {
 }
 
 VisualShader::VisualShader() {
+	dirty.set();
 	for (int i = 0; i < TYPE_MAX; i++) {
 		Ref<VisualShaderNodeOutput> output;
 		output.instance();
diff --git a/scene/resources/visual_shader.h b/scene/resources/visual_shader.h
index f3f3caf15e..ef724c7650 100644
--- a/scene/resources/visual_shader.h
+++ b/scene/resources/visual_shader.h
@@ -32,6 +32,7 @@
 #define VISUAL_SHADER_H
 
 #include "core/string/string_builder.h"
+#include "core/templates/safe_refcount.h"
 #include "scene/gui/control.h"
 #include "scene/resources/shader.h"
 
@@ -99,7 +100,7 @@ private:
 
 	static RenderModeEnums render_mode_enums[];
 
-	volatile mutable bool dirty = true;
+	mutable SafeFlag dirty;
 	void _queue_update();
 
 	union ConnectionKey {