Driver: Handle errors during texture creation (#16565)

The OpenGL drivers do accept 'nullptr' textures, however the
recent Mip-Mapping change did not respect that.
Furthermore, errors during texture creation for the pipeline are
now properly handled and shown as an error to the user.

irr/src/COpenGLDriver.cpp

@@ -2672,7 +2672,8 @@ bool COpenGLDriver::setRenderTargetEx(IRenderTarget *target, u16 clearFlag, SCol
 		// Update mip-map of the generated texture, if enabled.
 		auto textures = CurrentRenderTarget->getTexture();
 		for (size_t i = 0; i < textures.size(); ++i)
-			textures[i]->regenerateMipMapLevels();
+			if (textures[i])
+				textures[i]->regenerateMipMapLevels();
 	}
 
 	bool supportForFBO = (Feature.ColorAttachment > 0);

irr/src/OpenGL/Driver.cpp

@@ -1704,8 +1704,10 @@ bool COpenGL3DriverBase::setRenderTargetEx(IRenderTarget *target, u16 clearFlag,
 	if (CurrentRenderTarget) {
 		// Update mip-map of the generated texture, if enabled.
 		auto textures = CurrentRenderTarget->getTexture();
-		for (size_t i = 0; i < textures.size(); ++i)
+		for (size_t i = 0; i < textures.size(); ++i) {
-			textures[i]->regenerateMipMapLevels();
+			if (textures[i])
+				textures[i]->regenerateMipMapLevels();
+		}
 	}
 
 	core::dimension2d<u32> destRenderTargetSize(0, 0);

src/client/render/pipeline.cpp

@@ -5,6 +5,7 @@
 #include "pipeline.h"
 #include "client/client.h"
 #include "client/hud.h"
+#include "gettext.h"
 #include "IRenderTarget.h"
 #include "SColor.h"
 
@@ -85,7 +86,12 @@ void TextureBuffer::reset(PipelineContext &context)
 	for (u32 i = 0; i < m_definitions.size(); i++) {
 		video::ITexture **ptr = &m_textures[i];
 
-		ensureTexture(ptr, m_definitions[i], context);
+		if (!ensureTexture(ptr, m_definitions[i], context)) {
+			throw ShaderException(
+				fmtgettext("Failed to create the texture \"%s\" for the rendering pipeline.",
+					m_definitions[i].name.c_str()) +
+				strgettext("\nCheck debug.txt for details."));
+		}
 		m_definitions[i].dirty = false;
 	}