Fixes logically dead code (Coverity)

Fixes reported logically dead codes by Coverity

* image.cpp: Doesn't really need any modification. But to remove the bug
report then we have to move the MAX call away from the for loop
statement.

* rasterizer_gles3.cpp: Removes unnecessary elif condition since it is
checked earlier in the function

* collada.cpp: If stamement never reached due to macro ERR_CONTINUE does
the same.

* navigation_mesh.cpp: Variables should always be null - however, also
checked for the very same condition in their function call. Leaving this
for review (whether the function call is necessary or not)

* path_editor_plugin.cpp: If cancel is true, then it should restore the
edited value to the original provided.
http://docs.godotengine.org/en/3.0/classes/class_editorspatialgizmo.html#class-editorspatialgizmo-commit-handle

* spatial_editor_gizmos.cpp: the very condition of i >= 3 is
predetermined in the if case right before it. Thus case 1 is always '1'
and case 2 is always '-1'

* grid_map_editor.cpp: Same as above in spatial_editor_gizmos.cpp

* voxel_light_baker.cpp: Same as above in spatial_editor_gizmos.cpp

* visual_server.cpp: Same as above in spatial_editor_gizmos.cpp

* visual_script_expression.cpp: char '-' is already true in the switch
case mechanism. Thus it can never reach to default case.

* particles.cpp: Case 'PARAM_MAX' is unreachable due to index checking
right before the switch execution.

* shader_language.cpp: Invalid index is handled in switch default case.
`type < TYPE_FLOAT && type > TYPE_VEC4` -> `(type < TYPE_FLOAT || type > TYPE_VEC4`)
Fixes the "always false problem" in TODO comment.

1 files changed, 5 insertions, 10 deletions

diff --git a/servers/visual/shader_language.cpp b/servers/visual/shader_language.cpp
index 7aca497881..01cf689a09 100644
--- a/servers/visual/shader_language.cpp
+++ b/servers/visual/shader_language.cpp
@@ -2677,7 +2677,6 @@ ShaderLanguage::Node *ShaderLanguage::_parse_expression(BlockNode *p_block, cons
 					return NULL;
 				}
 
-				bool index_valid = false;
 				DataType member_type = TYPE_VOID;
 
 				switch (expr->get_datatype()) {
@@ -2696,7 +2695,7 @@ ShaderLanguage::Node *ShaderLanguage::_parse_expression(BlockNode *p_block, cons
 							_set_error("Only integer constants are allowed as index at the moment");
 							return NULL;
 						}
-						index_valid = true;
+
 						switch (expr->get_datatype()) {
 							case TYPE_BVEC2: member_type = TYPE_BOOL; break;
 							case TYPE_VEC2: member_type = TYPE_FLOAT; break;
@@ -2721,7 +2720,7 @@ ShaderLanguage::Node *ShaderLanguage::_parse_expression(BlockNode *p_block, cons
 							_set_error("Only integer constants are allowed as index at the moment");
 							return NULL;
 						}
-						index_valid = true;
+
 						switch (expr->get_datatype()) {
 							case TYPE_BVEC3: member_type = TYPE_BOOL; break;
 							case TYPE_VEC3: member_type = TYPE_FLOAT; break;
@@ -2745,7 +2744,7 @@ ShaderLanguage::Node *ShaderLanguage::_parse_expression(BlockNode *p_block, cons
 							_set_error("Only integer constants are allowed as index at the moment");
 							return NULL;
 						}
-						index_valid = true;
+
 						switch (expr->get_datatype()) {
 							case TYPE_BVEC4: member_type = TYPE_BOOL; break;
 							case TYPE_VEC4: member_type = TYPE_FLOAT; break;
@@ -2760,11 +2759,6 @@ ShaderLanguage::Node *ShaderLanguage::_parse_expression(BlockNode *p_block, cons
 					}
 				}
 
-				if (!index_valid) {
-					_set_error("Invalid index");
-					return NULL;
-				}
-
 				OperatorNode *op = alloc_node<OperatorNode>();
 				op->op = OP_INDEX;
 				op->return_cache = member_type;
@@ -3662,7 +3656,8 @@ Error ShaderLanguage::_parse_shader(const Map<StringName, FunctionInfo> &p_funct
 					_set_error("void datatype not allowed here");
 					return ERR_PARSE_ERROR;
 				}
-				if (!uniform && type < TYPE_FLOAT && type > TYPE_VEC4) { // FIXME: always false! should it be || instead?
+
+				if (!uniform && (type < TYPE_FLOAT || type > TYPE_VEC4)) {
 					_set_error("Invalid type for varying, only float,vec2,vec3,vec4 allowed.");
 					return ERR_PARSE_ERROR;
 				}